1. Field of the Invention
The present invention relates to acquisition of a tomographic image using interference of light. In particular, the present invention relates to a technique for adjusting the position of a coherence gate.
2. Description of the Related Art
An optical coherence tomography (OCT) technique using interference of multi-wavelength light enables acquisition of a high-resolution tomographic image of a sample, such as a human eye.
An OCT apparatus acquires the images of a subject's eye, an internal organ employing an endoscope, and the skin. Further, in recent years, there have been attempts to acquire, using the OCT apparatus, an OCT image that indicates optical characteristics and movement of a fundus tissue in addition to a normal OCT image representing the shape of the fundus tissue.
International Publication No. WO 2010/122118 A1 discusses a polarization sensitive OCT, which is an example of the OCT. The polarization sensitive OCT employs, as a measuring beam for examining the sample, a light beam that has been modulated to a circularly-polarized beam. Detection is then performed by splitting the interference beam into two linearly-polarized beams perpendicular to each other, so that the polarization sensitive OCT image is generated.
Further, there has been an understanding that the polarization sensitive OCT is capable of acquiring different types of information from the conventional OCT, and clinical research is being conducted therein.
When the subject is imaged using OCT, adjustment of an optical path length difference by positioning the coherent gate becomes crucial.
However, there are cases where elements configuring the subject cannot be extracted by only using the conventional OCT image information. In such a case, positioning of the coherent gate for imaging such elements may become troublesome.